Index this cubic powder diffraction pattern



Name (pinyin please)_______________________

Homework #2. If you get your work to me by Monday evening, we can discuss it in class Tuesday morning…..before the exam on Wednesday.

It will be OK if you want to email your work to me at rx7@psu.edu

1. Construct the two point group diagrams for the point group 32.

symmetry elements equivalent points

2. CaF2 is Fm3m, a = 5.462 Å, Ca in 4 a, F in 8c. Make a drawing of the crystal structure projected down [001]. The equipoints for space group Fm3m are listed on the next page.

The F atoms have how many Ca nearest neighbors (i.e., how many Ca atoms

touch each F atom)?

Since a = 5.462 Å, what is the Ca-F bond distance? (A simple geometry

calculation.)

3. A monoclinic crystal has a = 6, b = 4, c = 10 Å, ( = 110°. Make a rough drawing of a portion of the k = 0 level of the reciprocal lattice. Show and name the reciprocal lattice vectors and angle for the reciprocal lattice unit cell.

In a powder diffractometer, give the function (tell what it does) of the:

divergence slit

receiving slit

Soller slits

monochromator

5. Index this cubic powder diffraction pattern on the next page.

Give the Bravais lattice.

Calculate the lattice parameter for this material. Show your calculations.

l = 1.54184 Å.

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